TELOS 2101 USER’S MANUAL
PART IV
THE STUDIO INTERFACE & ADDITIONAL HYBRIDS
IV-35
SECTION 1 – STUDIO INTERFACE INSTALLATION
•
A built in 1k
Ω
pull up resistor is provided so TTL outputs can be directly
interfaced. See below for a simplified schematic of the input circuitry.
3 0 v m ax
+5V
Parallel logic input circuit
t
DEEP TECH NOTE!
The Studio Interface’s “universal” logic input circuit can be used with switch or relay
closures, voltage levels up to 24 Vdc, or logic outputs – either “totem- pole” or open-
collector.
Outputs
Outputs are open collector to ground and can sink up to 400 mA of current. Their
functions are shown on the previous page.
These will require a pull-up resistor to function with other logic inputs. Some
equipment has the pull-ups built into their control inputs – check the device’s manual
to be sure. If there is no pull-up in the interfaced equipment, you’ll have to add one.
An appropriate value is 2.2K
Ω
.
Current should be limited to 400ma maximum per output with total output restricted
to 1 amp (200ma each output if all five will be used). A safety diode internal to the
output component limits all external control voltages to 5 VDC.
If used with a relay or LED, then tie your external 5 VDC power source ground to
pin 1 (or use the 5 VDC power supplied on pin 8) and run this power source through
your device, with a resistor in series to limit maximum current to 400mA or less. For
external devices requiring greater than 5 VDC for operation you need to buffer the
input using some other 5 VDC device to prevent an over-voltage situation on the
output pins. Excess current from this over-voltage will damage the outputs.
